A projection display apparatus such as a rear projection TV causes an image distortion resulting from a positional relationship between a screen and a projection light source, or aberration or the like that is generally inherent in any optical system. To correct the distortion, techniques to project light of an image created by applying an inverse distortion characteristic to the distortion are conventionally known.
As one of the techniques, there is a technique for correcting image data by electrical signal processing; for instance, proposed is a liquid crystal projector that corrects image distortion by changing, on a predetermined scan line number basis, the number of pixels in scan lines of input images in order to correct keystone distortion.
A method of varying the number of pixels includes one in which the pixel number is varied by interpolating pixel data between each pair of sample pixel data adjacent to each other in a scan line of the input image (refer to, for instance, Japanese Unexamined Patent publication No. H08-102900 (paragraphs 0012, 0014, 0027 and 0040; FIGS. 3, 4, 12 and 13).
A problem with the conventional technique in the foregoing description, however, is that when image data containing a high frequency (HF) component such as a checkered pattern is supplied, moiré occurs in an output image, owing to aliasing resulting from re-sampling at a pixel position after conversion of an original image, thus leading to very bad-looking images.
In light of the foregoing description, the present invention provides an image processing apparatus, an image processing method and an image display apparatus, whereby image signals can be generated such that favorable display images are achieved even when digitized images are partially magnified or reduced as in keystone distortion correction.